The objective of this proposal is to investigate the signaling pathways that give rise to tumors in tuberous sclerosis complex (TSC). Approximately 50,000 Americans and more than a million people worldwide suffer from TSC, an autosomal dominant syndrome that affects multiple organ systems. Afflicted individuals suffer complications such as seizures, renal hemorrhage, and respiratory failure as a result of abnormal growths in the brain, kidneys and lung, among others. Treatment is palliative and no effective cure is known. Genetic research has identified two genes that are responsible for TSC, and recent studies have revealed their role in regulating two signaling pathways: the mTOR and beta-catenin signaling. However, there is a paucity of evidence to link the mTOR pathway to tumor development and abnormal beta-catenin activity to TSC pathology in vivo. The central hypothesis is that aberrant activity of both pathways leads to tumorigenesis. Using a combination of cellular, genetic and pharmacologic approaches, we propose to analyze the relative contribution of each of these two pathways in the pathogenesis of TSC-related tumors. The specific aims are 1) to assess the components of the mTOR and beta-catenin pathways in modulating tumorigenicity of Tsc2-1- cells, 2) to investigate genetic interaction between Tsc2 and components of the two pathways, and 3) to elucidate the role of mTOR during tumor initiation. Together, results of these experiments will provide a better appreciation of the in vivo relevance of these two signaling cascades in TSC biology. Our long-term goal is to exploit the mechanisms of these pathways in the development of clinical therapy for TSC-related disorders.